A trivial, conventional solution of the above mentioned information handling problem resides in that the execution of the second sequence is not started until the execution of the first sequence is terminated. This trivial solution is obtained as a natural necessity in a data processing system controlled by a single processor such that the sequences are executed one at a time using main memory locations common to both sequences.
It is known to increase data processing capacity by parallel execution of the instruction sequences. As long as the sequences are guaranteed in advance to be mutually independent, fault-free parallel operation is achieved with the aid of so-called pre-processing or multi-processing, or also with the aid of a one-processor system which includes at least two data processing units, each of which executes its instruction sequence. It is known to realize information handling both by means of a main memory which is common to a plurality of data processing units and by means of a plurality of separate memories each associated with its data processing unit and mutually updated from time to time.
When there are sensitive instruction sequences which affect each other, and which must therefore be executed in a prescribed order, e.g., according to the journal Computer Design, Aug. 15, 1985, pp 76-81, or "Balance 8000 System Technical Summary, Sequent Computer Systems, Inc", programming languages, compilers and sequence hardware for parallel processing of mutually independent sequences, are used while parallel processing of the sensitive sequences is prevented.